We've used Sonicare for years, decades actually. It has made a huge difference for us. I used to need 4 cleanings/year -- now I go 2x/yr. When I was manually brushing, I ended up needing some oral surgery for gingivitis pockets, but I have had no such problems after starting the Sonicare. Ditto for DS, whose pediatric dentist would always complain about his dental hygiene until he started using it. It cleans more thoroughly yet more gently than manual brushing, at least how I brush, & the 2 minute vibration marker lets me know I've done enough.
We've never purchased one from a dentist. Amazon or Sam's Club are good sources.